Function Analysis Of A Heme Peroxidase Gene Nl25323 In Nilaparvata Lugens

Heme peroxidases play important roles in growth, development, fecundity and innate immunity in insects. The brown planthopper (BPH), Nilaparvata lugens (Stal) (Hemiptera:Delphacidae) is one of the most destructive pests in rice. To ensure the yield and quality of rice, developing effective methods for Controltrolling BPH are urgent. In this study, using two BPH populations that were rared on Mudgo, a rice variety Controltaining a resistant gene Bph1, and TN1, a susceptible variety, respectively, the roles of a BPH heme peroxidase gene N125323 in survival, feeding, fecundity and innate immunity in BPH was investigated. Results are as follows.We cloned a BPH heme peroxidase gene N125323. The gene Controltains a 1560bp opening reading frame (ORF) which encodes a protein with 519 amino acids and with a predicted molecular weight of 58.9KDa and a theoretical pI of 5.61. Sequence analysis indicated that this protein has two LRE integrin binding sites, heme binding sites and Ca2+ binding sites, but has not a signal peptide and transmembrance domains. Transcriptional analysis revealed that N125323 was highly expressed in BPH head compared with other tissues and has higher mRNA levels in the fifth nymphs and newly emerged adults than in other developmental stages. Injection of Escherichia coli didn’t induce the expression of N125323. In addition, the expression levels of N125323 in the head and salivary gland of the BPH population from Mudgo was higher than that of the BPH population from TN1. Silencing of N125323 decreased the survival rate of nymphs of both BPH populations and the survival rate was dependent on the rice resistance level. Meanwhile, silencing N125323 reduced the amount of honeydew and the fecundity of female BPH adults from Mudgo population, but didn’t affect the level of H2O2 in BPH. The results indicate that N125323 plays an important role in the growth, development, survival and fecundity of BPH, and the N125323 may also be related to the change in BPH virulence. However, the roles played by N125323 as stated above are unrelated with the removal of H2O2 from BPH. The mechanism on how N125323 influences the growth, development, survival and fecundity of BPH needs to be further investigated.